The pint- sized powerhouse: Illuminating the mighty role of the gut microbiome in improving the outcome of anti- cancer therapy

Abstract

Cancer persists as a major health catastrophe and a leading cause of widespread mortality across every nation. Research of several decades has increased our understanding of the pivotal pathways and key players of the host during tumor development and progression, which has enabled generation of precision therapeutics with improved efficacy. Despite such tremendous advancements in our combat against this fatal disease, a majority of the cancer patients suffer from poor tumor- free survival owing to the increased incidence of recurrent tumor. This is primarily due to the development of resistance against contemporary anti- cancer strategies. Recent studies have pointed towards the involvement of the human symbiotic gut microbiota in regulating the outcome of chemotherapy and immunotherapy. It does so primarily by modulating the metabolism of the drugs and host immune response, thereby enhancing the efficacy and ameliorating the toxicity. The interactions between the therapeutic agents, microbial community and host immunity may provide a new avenue for the clinical management of cancer. In addition, consumption of dietary pro-, pre- and synbiotics has been recognized to confer protection against tumor genesis and also promote improved response to traditional tumor suppressive strategies. Naturally, the use of various combinatorial regimes containing dietary supplements that improve the gut microbiome in amalgamation with conventional cancer treatment methods may significantly augment the therapeutic outcome of cancer patients and circumnavigate the resistance mechanisms that confound traditional therapies. In this review, we have summarized the role of the gut microbiome, which is the largest assembly of commensals within the human body, in regulating the efficacy and toxicity of various existing anti- cancer therapies including chemotherapy, immunotherapy and surgery. Furthermore, we have discussed how novel strategies integrating the application of probiotics, prebiotics, synbiotics and antibiotics in combination with the aforementioned anti- cancer modules manipulate the gut microbiota and, therefore, augment their therapeutic outcome. Together, such innovative anti- tumorigenic approaches may prove highly effective in improving the prognosis of cancer patients.

Keywords: Anti- cancer therapy; Chemotherapy; Gut microbiome; Immunotherapy; Microbiota.